Fix Writer bug not properly handling LINE_END comments with `WRITE_…

…NEWLINES` (#88)

build.gradle

@@ -136,6 +136,10 @@ dependencies {
 	testImplementation group: "com.google.code.findbugs", name: "jsr305", version: "3.0.2";
 }
 
+test {
+	useJUnitPlatform()
+}
+
 signing {
 	if (project.hasProperty("signing.keyId")) {
 		println("Key credentials found. Enabling jar signing.");

src/main/java/blue/endless/jankson/api/io/JsonWriter.java

@@ -125,6 +125,7 @@ private void writeComment(String value, CommentType type) throws IOException {
 			addCommas();
 			write("//");
 			write(value);
+			skipNewline = false;
 			writeNewline();
 			break;
 

src/test/java/blue/endless/jankson/TestJsonCommentNewline.java

@@ -0,0 +1,64 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018-2024 Falkreon (Isaac Ellingson)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package blue.endless.jankson;
+
+import blue.endless.jankson.api.Jankson;
+import blue.endless.jankson.api.SyntaxError;
+import blue.endless.jankson.api.document.*;
+import blue.endless.jankson.api.io.JsonWriterOptions;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+public class TestJsonCommentNewline {
+    private static final JsonWriterOptions JSON_WRITER_OPTIONS = new JsonWriterOptions("    ",
+            JsonWriterOptions.Hint.WRITE_COMMENTS, JsonWriterOptions.Hint.WRITE_NEWLINES);
+    private static final String EXPECTED_RESULT = """
+            {
+                // Comment
+                "key": "value"
+            }""";
+
+    @Test
+    public void testJsonCommentNewlineWriter() throws SyntaxError, IOException {
+        ObjectElement objectElement = new ObjectElement();
+        KeyValuePairElement keyValuePairElement = new KeyValuePairElement("key", PrimitiveElement.of("value"));
+        keyValuePairElement.getPrologue().add(new CommentElement(" Comment", CommentType.LINE_END));
+        objectElement.add(keyValuePairElement);
+        StringWriter stringWriter = new StringWriter();
+        Jankson.writeJson(objectElement, stringWriter, JSON_WRITER_OPTIONS);
+        Assertions.assertEquals(EXPECTED_RESULT, stringWriter.getBuffer().toString());
+    }
+
+    @Test
+    public void testJsonCommentNewlineReaderWriter() throws SyntaxError, IOException {
+        ValueElement valueElement = Jankson.readJson(EXPECTED_RESULT);
+        StringWriter stringWriter = new StringWriter();
+        Jankson.writeJson(valueElement, stringWriter, JSON_WRITER_OPTIONS);
+        Assertions.assertEquals(EXPECTED_RESULT, stringWriter.getBuffer().toString());
+    }
+}